音色 is basically OK, but there's always a strong feeling of mismatch when PLL partnering with other brand's power amps, no matter it's Mark, cj, Passlabs, etc. First of all, it's all too "清通", too "明亮", up to a point of uneasiness. And 2nd problem is the gain setting. You cannot easily match other power amp's sensitivity using either +20db or -20db setting inside the PLL. In the end, I would say the best matching power amps for Nagra pre must be it's own products.
Nagra PLL with my other cj premier16 preamp........